The present invention relates to a frozen food to be microwave-heated. More particularly, the present invention relates to a frozen fried food to be microwave-heated which is endurable for freeze-preservation.
Also, the present invention relates to a fried food which can remarkably suppress moisture absorption of coating and/or sheet not only immediately after production but also during freeze-preservation, and which can maintain crispness in eating even when the food has been heated again by a microwave oven after the preservation.
In the present invention, the term xe2x80x9cfreezingxe2x80x9d means temperatures below 0xc2x0 C.
Generally, it is important in fried foods that their coating and/or sheet (hereinafter called xe2x80x9ccoatingsxe2x80x9d) provide crispness when eaten. Such crispness in eating can be usually obtained in fried foods immediately after being externally heated by, e.g., frying or using a toaster oven. On the other hand, cooing utilizing internal heating with a microwave oven has a difficulty in providing the crispness in eating because the xe2x80x9ccoatingsxe2x80x9d absorb water vapor evaporated from the interior of a food during the cooking.
Recently, various techniques have been proposed as means for preventing xe2x80x9ccoatingsxe2x80x9d from absorbing moisture when frozen foods are cooked by a microwave oven. As a result, some techniques have succeeded in suppressing moisture absorption of xe2x80x9ccoatingsxe2x80x9d at a satisfactory level immediately after freezing or after freeze-preservation under a condition below xe2x88x9230xc2x0 C. Even with application of those techniques, there still remains such a problem that, when frozen fried foods are preserved at temperatures higher than xe2x88x9230xc2x0 C., xe2x80x9ccoatingsxe2x80x9d absorb moisture during freeze-preservation before the frozen foods are microwave-heated, and crispness is deteriorated.
In the case of producing frozen fried foods, each of which is to be microwave-heated and comprises a food substrate and xe2x80x9ccoatingsxe2x80x9d , there are two major problems. The first problem is that the xe2x80x9ccoatingsxe2x80x9d forming an outer surface of the food absorbs moisture evaporated from the interior of the food during microwave heating. The second problem is that the xe2x80x9ccoatingsxe2x80x9d absorbs moisture during freeze-preservation.
Those phenomena are disadvantageous in changing the texture of the food after being microwave-heated, particularly a texture of the xe2x80x9ccoatingsxe2x80x9d, into a gummy or loose texture without crispness, and hence providing a poor texture far from that of foods just after being fried.
Of the above two problems, the second problem of xe2x80x9cmoisture absorption of the xe2x80x9ccoatingsxe2x80x9d during freeze-preservationxe2x80x9d is recognized as a major problem only after the first problem of xe2x80x9cmoisture absorption of the xe2x80x9ccoatingsxe2x80x9d during microwave heatingxe2x80x9d has been solved.
In other words, only those persons, who have techniques capable of reproducing a good texture when frozen foods are cooked by a microwave oven immediately after freezing, can recognize that the good texture is not reproduced when the frozen foods are cooked by a microwave oven after freeze-preservation at temperatures higher than xe2x88x9230xc2x0 C. Accordingly, the above two problems must be solved for producing frozen fried foods to be microwave-heated at a level nearer to perfection.
There have been proposed various techniques for dealing with the first problem of xe2x80x9cmoisture absorption of the xe2x80x9ccoatingsxe2x80x9d during microwave heatingxe2x80x9d of the above two problems. One preferable technique is to employ a batter composition, which contains heat treatment flour, high-amylose starch, etc., for xe2x80x9ccoatingsxe2x80x9d. More preferably, the batter composition contains dextrin and an emulsifier in addition to the above components. It has been confirmed that, when foods are fried using the batter having such a composition, the formed coating have a porous structure. Because of the porous structure, moisture evaporated when the fried food is microwave-heated after freezing is allowed to escape to the outside of the food through the coating, and therefore moisture absorption of the coating during the microwave heating is suppressed. By employing the above technique, the frozen fried foods can provide crispness, when microwave-heated, comparable to that obtainable with externally heated foods. As a matter of course, the second problem of xe2x80x9cmoisture absorption of the xe2x80x9ccoatingsxe2x80x9d during freeze-preservationxe2x80x9d cannot be recognized as an explicit problem without utilizing the above technique. This is because it is not clear that disappearing of the crispness is attributable to which one of moisture absorption during microwave heating or moisture absorption during freeze-preservation.
An object of the present invention is therefore to provide a frozen fried food which is substantially free from the occurrence of transfer of moisture from a food substrate to xe2x80x9ccoatingsxe2x80x9d such as, in particularly, a sheet and a coating not only immediately after the food has been frozen, but also when the food is freeze-preserved at a comparatively high temperature and after the food has been freeze-preserved for a long period of time, and which is capable of preventing a decrease in crispness of the xe2x80x9ccoatingsxe2x80x9d after the food has been cooked by a microwave oven. Another object of the present invention is to provide xe2x80x9ccoatingsxe2x80x9d suitable for microwave heating, a vapor pressure regulating technique, and a technique for preventing moisture absorption during freeze-preservation, which are necessary for producing the frozen fried food.
As a result of intensively conducting studies to achieve the above objects, the inventors have found that the crispness of the xe2x80x9ccoatingsxe2x80x9d can be maintained even when the frozen fried food is freeze-preserved at a comparatively high temperature, by employing the xe2x80x9ccoatingsxe2x80x9d suitable for microwave heating which does not easily absorb moisture evaporated during the microwave heating, treating the food substrate with a coating layer agent having a low vapor permeability, and placing a moisture absorbent in a food package during freeze-preservation. The present invention has been accomplished based on the above finding.
The present invention resides in a coating layer agent composition for frozen foods to be microwave-heated, each of the foods comprising a food substrate and a xe2x80x9ccoatingsxe2x80x9d, wherein the composition contains an emulsifier, preferably acetylated monoglycerides and/or protein, and/or oil and fat. The composition can be used in the form of powder mixed with and adhered to silicon dioxide. Accordingly, the present invention resides in a coating layer agent composition for frozen foods to be microwave-heated, each of the foods comprising a food substrate and a xe2x80x9ccoatingsxe2x80x9d, wherein the composition contains an emulsifier, and/or acetylated monoglycerides and/or protein, and/or oil and fat, the composition being preferably in the form of powder mixed with and adhered to silicon dioxide. The composition contains a coating layer agent preferably in the range of 100-250 weight % for silicon dioxide. Accordingly, the present invention resides in a coating layer agent composition for frozen foods to be microwave-heated, each of the foods comprising a food substrate and a xe2x80x9ccoatingsxe2x80x9d, wherein the composition contains an emulsifier, preferably acetylated monoglycerides and/or protein, and/or oil and fat, the composition being in the form of powder mixed with and adhered to silicon dioxide in the range of 100-250 weight % for silicon dioxide. The composition may further contain thermo-coagulating protein. Accordingly, the present invention resides in a coating layer agent composition for frozen foods to be microwave-heated, each of the foods comprising a food substrate and a xe2x80x9ccoatingsxe2x80x9d, wherein the composition contains an emulsifier, preferably acetylated monoglycerides and/or proteins, and/or oil and fat, as well as thermo-coagulating protein, the composition being in the form of powder mixed with and adhered to silicon dioxide preferably in the range of 100-250 weight % for silicon dioxide.
Also, the present invention resides in a frozen food to be microwave-heated, which comprises a food substrate and a xe2x80x9ccoatingsxe2x80x9d, wherein a layer of a coating layer agent capable of maintaining a low vapor permeability after cooking by microwave heating and during freeze-preservation of the food, is interposed between the food substrate and the xe2x80x9ccoatingsxe2x80x9d. The coating layer agent contains an emulsifier, preferably acetylated monoglycerides and/or protein, and/or oil and fat. Accordingly, the present invention resides in a frozen food to be microwave-heated, each of the foods comprising a food substrate and a xe2x80x9ccoatingsxe2x80x9d, wherein a layer of a coating layer agent capable of maintaining a low vapor permeability after cooking by microwave heating and during freeze-preservation of the food is interposed between the food substrate and the xe2x80x9ccoatingsxe2x80x9d, the coating layer agent containing an emulsifier, preferably acetylated monoglycerides and/or protein, and/or oil and fat. The coating layer agent may be used in the form of powder mixed with and adhered to silicon dioxide. Accordingly, the present invention resides in a frozen food to be microwave-heated, each of the foods comprising a food substrate and a xe2x80x9ccoatingsxe2x80x9d, wherein a film of a coating layer agent capable of maintaining a low vapor permeability after cooking by microwave heating and during freeze-preservation of the food is interposed between the food substrate and the xe2x80x9ccoatingsxe2x80x9d, the coating layer agent containing an emulsifier, preferably acetylated monoglycerides and/or protein, and/or oil and fat, and being preferably in the form of powder mixed with and adhered to silicon dioxide. The powder contains the coating layer agent in the range of 100-250 weight % for silicon dioxide. The powder may further contain thermo-coagulating protein.
Further, according to the present invention, the frozen food to be microwave-heated is in the form of a deep-fried food with a coating or a sheet formed. Thus, the present invention resides in a frozen food to be microwave-heated, each of the foods comprising a food substrate and a xe2x80x9ccoatingsxe2x80x9d and being in the form of a deep-fried food with a coating or a sheet formed, wherein a layer of a coating layer agent capable of maintaining low a vapor permeability after cooking by microwave heating and during freeze-preservation of the food is interposed between the food substrate and the xe2x80x9ccoatingsxe2x80x9d.
The xe2x80x9ccoatingsxe2x80x9d is designed to be adapted for microwave heating, and preferably contains any of heat treatment flour, dextrin and high-amylose starch. Thus, the present invention resides in a frozen food to be microwave-heated, each of the foods comprising a food substrate and a xe2x80x9ccoatingsxe2x80x9d and being in the form of a deep-fried food with a coating or a sheet, the coat being designed to be adapted for microwave heating and preferably containing any of heat treatment flour, dextrin and high-amylose starch, wherein a layer of a coating layer agent capable of maintaining a low vapor permeability after cooking by microwave heating and during freeze-preservation of the food is interposed between the food substrate and the xe2x80x9ccoatingsxe2x80x9d. The emulsifier of the xe2x80x9ccoatingsxe2x80x9d may be fatty acid ester of polyglycerin or sucrose ester. Also, the emulsifier preferably has an HLB value not higher than 10. Preferable concrete examples of the heated food with a coating or a sheet, according to the present invention, include spring rolls, croquettes, fries, fritters, deeply fried foods, and fried foods with thin xe2x80x9ccoatingsxe2x80x9d. Moreover, when the frozen food is provided in the packaged form, a moisture absorbent is placed in a food package. The frozen food to be microwave-heated of the present invention is adapted for freeze-preservation preferably at temperatures not lower than xe2x88x9230xc2x0 C., i.e., at temperatures where the saturated vapor pressure is not lower than 0.29 mmHg. More preferably, the frozen food to be microwave-heated of the present invention is adapted for freeze-preservation at temperatures where the saturated vapor pressure is not lower than 0.79 mmHg.
Foods, to which the present invention is applied, are any desired heated foods each comprising a food substrate and a xe2x80x9ccoatingsxe2x80x9d, which are suitable for being frozen and must be crispy in part or entirety thereof after being heated by a microwave oven.
Appropriate examples of those foods are fried-in-oil foods with xe2x80x9ccoatingsxe2x80x9d. Specifically, those examples include fried foods with batter and bread crumb applied to their surfaces, such as croquettes and fries, fried foods with batter, bread crumb and other suitable coat materials covering their surfaces, such as fritters, deeply fried foods, and fried foods with thin coats; and rolled foods including foods substrates, similarly to the above coated foods, which are rolled by sheets.
Moisture absorption of xe2x80x9ccoatingsxe2x80x9d of fried foods or sheets of rolled foods during freeze-preservation occurs as such a phenomenon that water vapor sublimated from food substrates having a high moisture content is absorbed by the xe2x80x9ccoatingsxe2x80x9d, which mainly comprise flour and/or starch and have a low moisture content. Therefore, an extent of the moisture absorption perfectly depends on a saturated vapor pressure (saturated sublimated vapor pressure) at the temperature during the freeze-preservation.
Saturated vapor pressures of ice are given, for example, by xe2x88x9250xc2x0 C.=0.03 mmHg, xe2x88x9230xc2x0 C.=0.29 mmHg, xe2x88x9220xc2x0 C.=0.79 mmHg, and xe2x88x9210xc2x0 C.=1.95 mmHg. Thus, the saturated vapor pressure increases as the temperature rises (there is a relationship of function between a logarithm of the saturated vapor pressure of ice and the reciprocal of temperature on the bases of the Clapeyron""s equation; dP/dT=xcex94H/Txcex94V).
Accordingly, an extent of moisture absorption of the xe2x80x9ccoatingsxe2x80x9d during freeze-preservation also increases with a rise in temperature.
The vapor pressures under the frozen condition are lower values in comparison with those at the normal temperature. Considering practical freeze-preservation, however, when a frozen fried food is preserved at xe2x88x9210xc2x0 C., an atmosphere vapor pressure of the xe2x80x9ccoatingsxe2x80x9d is almost equal to the saturated vapor pressure =1.95 mmHg because of the presence of a food substrate having a high moisture content. The vapor pressure of 1.95 mmHg corresponds to a relative humidity of 11.1% at 20xc2x0 C. and 6.1% at 30xc2x0 C.
In other words, preserving frozen fried foods at xe2x88x9210xc2x0 C. is equivalent to preserving at 30xc2x0 C. with a relative humidity of 6.1%. Moisture of xe2x80x9ccoatingsxe2x80x9d of deep-fried foods such as croquettes is in the range of 5 to 10%. The example of flour and/or starch based food of which moisture is equal to that of croquettes and which is preserved at the normal temperature is Japanese rice cracker. When the rice cracker is preserved at 30xc2x0 C. with a relative humidity of 6.1%, an amount of moisture in the rice cracker after absorbing moisture is about 5 g/100 g (dry basis), and these rice cracker exhibit higher breaking stress than before the moisture absorption; namely, they are hardened. Among flour and/or starch based foods, cookie has less moisture, in the range of 2 to 3%, than that of xe2x80x9ccoatingsxe2x80x9d of frozen fried foods. As the rice cracker, however, the cookie also absorbs moisture and are softened when preserved at the same condition. Thus, the rice cracker and the cookie are both xe2x80x9cdampedxe2x80x9d by absorbing moisture. Similarly to the rice cracker and the cookie, the frozen fried foods are also xe2x80x9cdampedxe2x80x9d in a temperature range near xe2x88x9210xc2x0 C. where the saturated vapor pressure is high.
As a result of being damped, the crispness disappears (i.e., the foods are softened or hardened) and a gummy texture occurs (i.e., the breaking stress increases) when eating the foods.
Means for preventing the xe2x80x9ccoatingsxe2x80x9d from absorbing moisture during freeze-preservation are only realized by reducing the vapor pressure. The most effective means for that purpose is to lower the temperature. Another effective means is to suppress water vapor generated from food substrates that are vapor sources, or to absorb water vapor that has been generated.
The most effective means for reducing the vapor pressure is to lower the temperature. More specifically, for example, the saturated vapor pressure is 0.03 mm Hg at xe2x88x9250xc2x0 C. and 0.29 mmHg xe2x88x9230xc2x0 C. These saturated vapor pressures correspond respectively to 0.2% and 1.7% calculated in terms of a relative humidity at 20xc2x0 C. At these low levels of relative humidity, cookies, rice crackers and other similar foods are hardly moistened. xe2x80x9ccoatingsxe2x80x9d of frozen fried foods are also hardly moistened such low temperatures. A problem of moisture absorption of xe2x80x9ccoatingsxe2x80x9d of frozen fried foods occurs at temperatures of higher than xe2x88x9220xc2x0 C., especially higher than xe2x88x9210xc2x0 C., where the saturated vapor pressure is relatively high.
 less than With Regard to Coating Layer for Food Substrates greater than 
A conceivable method for suppressing water vapor generated from food substrates of the frozen fried foods is to cover the food substrates with coating layer. A coating layer agent for food substrate is employed to form a thin coating film, which has a low vapor permeability, around the food substrates. Usually, the thin coating film is stick to the food substrate and fulfills its function. However, the thin coating film may be stick to the xe2x80x9ccoatingsxe2x80x9d. In such condition, it is still effective so long as it is formed between the food substrate and the xe2x80x9ccoatingsxe2x80x9d.
An emulsifier or protein is used as the coating layer agent for the food substrate. If polysaccharides having high water solubility are used as the coating layer agent, a polysaccharide film would absorb moisture by itself and become a deteriorated-texture layer, and could not sufficiently suppress the generation of water vapor. Other disadvantages of polysaccharides are that the film strength would be reduced upon contacting with a better solution, and it would take a time to form the film. If fats, oils or waxes having a high hydrophobic property are used as the coating layer agent, there would occur such disadvantages that a film of the coating layer agent is melted upon frying in oil to disappear after the cooking, and a batter solution is hard to attach to the film of the coating layer agent. In view of the above, an emulsifier or protein having both hydrophilic and hydrophobic properties is suitable as the coating layer agent for food substrate. Preferably examples are acetylated monoglycerides as the emulsifier and casein as the protein. The acetylated monoglycerides are diacetates or monoacetates of monoglycerides of fatty acids. Preferable fatty acids include a lauric acid, myristic acid, oleic acid, palmitic acid, stearic acid, etc. Among these examples, the monoglyceride in which a fatty acid mainly comprises a stearic acid and a degree of acetylation is low is most preferable.
Other emulsifier is often used for emulsifying oil in water or water in oil. The emulsifier used in such a case has a high emulsifying capacity, but exhibits no or a very weak film forming ability in itself. The emulsifier used in the present invention is featured as no or very weak emulsifying capacity, but having a high film forming ability in itself.
 less than Form of Coating Layer Agent in Use greater than 
The coating layer agent can be used in any desired form, but it is preferably in the form of liquid or powder. When the coating layer agent is used in the form of liquid, it can be prepared by melting under heating or by adding a solvent such as ethanol, and is preferably applied by such methods as spraying, dipping or curtain coating. When the coating layer agent is used in the form of powder, the powder can be obtained by adsorbing the coating layer agent to a base material such as starch, fiber, silicon dioxide. Regarding base material, silicon dioxide is preferably from the viewpoints of stability and its water absorbing capacity. Further, the powder may be used solely or as a blend with another material such as thermo-coagulating protein. The powder is preferably applied to food substrates, for example, by spraying or sprinkling the powder.
 less than With Regard to Thermo-coagulating Protein Added greater than 
When foods with coating layers formed are fried, the xe2x80x9ccoatingsxe2x80x9d of the food sometimes detached from the food substrates. Such a phenomenon can be avoided by adding thermo-coagulating protein to the coating layer agent.
 less than Amount of Coating Layer Agent for Food Substrate Used greater than 
By adding the coating layer agent to such an extent that the food substrate is completely coated, the vapor pressure can be remarkably suppressed. Using the coating layer agent in such an amount however deteriorates the food in tastes and texture. From that point of view, therefore, the amount of the coating layer agent to be added is spontaneously restricted, and therefore a suppressing effects of the vapor pressure is limited. Incidentally, suppressing the vapor pressure by a coating layer has the same meaning as lowering the temperature during preservation.
Accordingly, in a preferable mode of the present invention, a frozen food to be microwave-heated is featured in that a food substrate is covered with a film of a coating layer agent, which does not absorb moisture, to which a batter solution adheres well, and which suppresses water vapor generated from the food substrate after frying in oil, freeze preservation, the coating layer agent containing an emulsifier, preferably acetylated monoglycerides and/or protein, and/or oil and fat, and microwave heating.
When the frozen food to be microwave-heated of the present invention is a deep-fried food with a xe2x80x9ccoatingsxe2x80x9d, the xe2x80x9ccoatingsxe2x80x9d is preferably designed to be adapted for microwave heating.
The xe2x80x9ccoatingsxe2x80x9d designed to be adapted for microwave heating contains any of heat treatment flour, dextrin and high-amylose starch. The xe2x80x9ccoatingsxe2x80x9d may further contain an emulsifier. Preferably examples of the emulsifier are fatty acid ester of polyglycerin and sucrose ester. Also, the emulsifier preferably has an HLB value not higher than 10.
 less than With Regard to Moisture Absorbent greater than 
A conceivable method for absorbing water vapor once generated is to place a moisture absorbent in a food package.
As described above, the amount of the coating layer agent to be added is spontaneously restricted from the viewpoints of taste and texture, and therefore a suppressing effect of the vapor pressure is limited. Hence, when the frozen fried food is in the packaged form, the moisture absorbent is placed in a food package to absorb water vapor once generated in combination with the use of the coating layer agent. The method of placing a material having a high moisture absorptivity, which is generally called a moisture absorbent or desiccating agent, in a package along with a fried food is effective in causing the moisture absorbent to absorb water vapor generated from a food substrate before the water vapor is absorbed by the xe2x80x9ccoatingsxe2x80x9d, and hence reducing a relative humidity at the temperature during preservation.
A reduction in relative humidity is equivalent to reducing the temperature during preservation from the standpoint of the saturated vapor pressure. For example, reducing the relatively humidity at xe2x88x9210xc2x0 C. to 40% is equivalent to preserving the food at xe2x88x9220xc2x0 C.
Such a method is effective because it is sample and is not required to be held in contact with the food. However, once the moisture absorbent has lost its ability of absorbing moisture, that is to say, the moisture absorbing ability has been saturated, the moisture absorbent is no longer effective. It is therefore practically impossible to solve the problem of xe2x80x9cmoisture absorption of a xe2x80x9ccoatingsxe2x80x9d during freeze-preservationxe2x80x9d by, as disclosed in Japanese Unexamined Patent Application Publication No. 5-64574, using the moisture absorbent along. Specifically, extension of a preservation period is related to an amount of the moisture absorbent used, and there exists competition on absorption of water vapor between the xe2x80x9ccoatingsxe2x80x9d and the moisture absorbent. Even if the moisture absorbent absorbs water vapor with priority, the xe2x80x9ccoatingsxe2x80x9d eventually start absorbing moisture after the moisture absorbent is saturated with moisture.
By placing the moisture absorbent in a package of the frozen fried food of the present invention, the frozen fried food can be virtually regarded as corresponding to a food which is freeze-preserved at temperatures not lower than xe2x88x9230xc2x0 C., i.e., at temperatures where the saturated vapor pressure is not lower than 0.29 mmHg. It is also possible to bring the frozen fried food into a condition equivalent to that of a food which is freeze-preserved at temperatures not lower than 20xc2x0 C., i.e., at temperatures where the saturated vapor pressure is not lower than 0.79 mmHg.
There are no restrictions on types of the moisture absorbent. Any of moisture absorbents generally used in foods, such as silica gel, quick lime, and calcium chloride, is usable. An amount of the moisture absorbent varies over a wide range depending on various factors such as the type of the moisture absorbent, the type of the food, the temperature during preservation, and the desired shell life. In general, an amount of the moisture absorbent is in the range of 1 to 80 weight %, more typically in the range of 2 to 20 weight %, on the basis of the food weight. The moisture absorbent may be in direct contact with the food in a package, or may be capsulated in a fine-porous plastic sheet having such a pore size as allowing water vapor to permeate through the sheet, but preventing particles of the moisture absorbent form passing through the sheet. The fine-porous plastic sheet is known to those skilled in the art, and can be manufactured from various plastic materials such as polyolefins, vinyl polymers, polyamides, polyurethanes, and polyesters.
The frozen fried food can be packaged using any usual package that is adapted for not only preservation under a frozen condition along with the moisture absorbent, but also reheating by a microwave oven. The package should be tight against water vapor, and may be a bag manufactured from materials such as polyurethanes, polyolefins, polyesters, and polyamides.
Moisture absorption of the xe2x80x9ccoatingsxe2x80x9d of the frozen fried food during microwave heating can be suppressed by making the xe2x80x9ccoatingsxe2x80x9d porous by frying in oil, because the porous structure allows moisture which come from the food when the fried food is microwave-heated after freezing to escape to the outside of the food through the xe2x80x9ccoatingsxe2x80x9d. Therefore, the frozen fried food exhibits crispness, when microwave-heated, comparable to that obtainable with externally heated foods. By employing, as a coating layer agent for the food substrate, an emulsifier, protein, etc. having both hydrophilic and hydrophobic properties, it is possible to form a film which does not absorb moisture by itself, but has such a property as allowing a batter solution to adhere well to the form, and which functions suppress water vapor from a food substrate after frying in oil. The coating layer agent is used in such an amount as not affecting the food in points of taste and texture.
By placing a material having a high moisture absorptivity, which is called a moisture absorbent or desiccating agent, in a package along with the fried food, water vapor generated from the food substrate can be absorbed by the moisture absorbent before the water vapor is absorbed by the xe2x80x9ccoatingsxe2x80x9d. As a result, a relative humidity at the temperature during preservation can be reduced.
When foods with coating layers formed are fried, the xe2x80x9ccoatingsxe2x80x9d of the food sometimes detached from the food substrates: Such a phenomenon can be avoided by adding thermo-coagulating protein to the coating layer agent.
Details of the present invention will be described in conjunction with Examples. It is to be noted that the present invention is limited in no way by the following Examples.